The single point mutation F198S in prion protein can induce aberrant 3-dimensional structure which finally lead to serious disease. One of the most significant differences between normal and abnormal structures is the concentration of alpha-helix and beta-sheet. By employing molecular dynamics method, we studied the structural transition induced by the mutation F198S. Our results show that the loss of the hydrophobic interactions between the 198-th residue and its surroundings may lead to the transition. A creation of additional beta-sheet is captured in our investigation which has not been reported in the dynamical studies of mutated induced structure conversion in prion protein. (c) 2005 Elsevier B.V All rights reserved.